In the automotive industry, proper vehicle quality requires measurement and adjustment of wheel alignment settings, both during manufacture and subsequently during the useful life of the vehicle. Proper positioning and alignment of vehicle wheels, and especially steerable wheels such as the front wheels of a vehicle, requires the setting of toe, camber angle, and caster angle. Toe is the angle between the vehicle's longitudinal axis and a plane through the center of the wheel/tire and affects the straight-ahead running of the vehicle as well as steering. Camber angle is the inclination of the wheel axis toward the road surface in a vertical. Caster angle influences lateral control, is typically moderately negative, and is the distance between the contact point of the wheel/tire with the road and the point at which the steering axis intersects the road as viewed from the side of the wheel. During assembly and/or repair of vehicles, it is important to measure, adjust or audit, and set the toe as well as the camber and caster angles of vehicle wheels, and especially steerable wheels, so the vehicle will drive and steer properly.
In the past, various methods have been used to measure toe and camber of vehicle wheels including direct and indirect methods. Direct measurement methods require human operators or mechanisms to place or mount measurement tools in contact with or to the vehicle and are subject to placement error and wear. Indirect measurement methods, sometimes referred to as noncontact methods, typically include the viewing or sensing of the image of light projected on a tire and the use of a computer to calculate the tire position from such images to provide the ultimate alignment information. While the prior known direct measurement methods were cumbersome, time-consuming, often labor-intensive, and less accurate than desired, the noncontact or indirect methods often required precisely located, relatively complex light and therefore expensive projectors as well as highly sophisticated calculation methods to determine the wheel and tire position.
Therefore, a need was determined for an apparatus and method for measuring and determining the orientation of a vehicle wheel and, more broadly, any three-dimensional object, which would allow rapid, accurate determination of the plane of the wheel or object in an efficient and less expensive manner to indicate the position of the wheel/tire with respect to the vehicle center line for purposes of setting the toe and/or camber of the wheel/tire for alignment purposes.